Cross-linking of porin with glutardialdehyde: a test for the adequacy of premises of cross-linking theory

Abdussalam Azem, Isabella Shaked, Jurg P. Rosenbusch, Ezra Daniel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Exposure of porin from Escherichia coli to glutardialdehyde followed by SDS-gel electrophoresis in 3% polyacrylamide yielded three bands that were identified in order of decreasing mobility as monomers and two and three cross-linked polypeptide chains. The distribution of protein among the three species for different extents of reaction showed a remarkably good agreement with corresponding values predicted from cross linking theory for an oligomer composed of three identical subunits arranged according to a 3-fold rotation axis. Electrophoresis performed in 7.5% polyacrylamide yielded four bands that were assigned to polypeptide chain monomers, dimers, and two types of trimers carrying two and three intersubunit cross-links. Our findings provide evidence that the central premise of cross-linking theory, viz. that the intersubunit cross-links formed upon exposure of a protein to a bifunctional reagent be governed by the symmetry of the molecule, is valid. Careful interpretation of cross-linking experiments thus proves an effective method to assess the oligomeric structure of a protein and reveal the symmetry underlying the spatial arrangement of the subunits within the molecule.

Original languageEnglish
Pages (from-to)151-156
Number of pages6
JournalBiochimica et Biophysica Acta - General Subjects
Volume1243
Issue number2
DOIs
StatePublished - 23 Feb 1995

Keywords

  • (E. coli)
  • Cross-linking theory
  • Glutardialdehyde
  • Polypeptide chain cross-linking
  • Porin

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